The rcu_data structure's ->gpwrap field is read locklessly, and so
this commit adds the required READ_ONCE() to a pair of laods in order
to avoid destructive compiler optimizations.
This data race was reported by KCSAN.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
rcu_lockdep_assert_cblist_protected(rdp);
c = rcu_seq_snap(&rcu_state.gp_seq);
- if (!rdp->gpwrap && ULONG_CMP_GE(rdp->gp_seq_needed, c)) {
+ if (!READ_ONCE(rdp->gpwrap) && ULONG_CMP_GE(rdp->gp_seq_needed, c)) {
/* Old request still live, so mark recent callbacks. */
(void)rcu_segcblist_accelerate(&rdp->cblist, c);
return;
continue;
for_each_leaf_node_possible_cpu(rnp, cpu) {
rdp = per_cpu_ptr(&rcu_data, cpu);
- if (rdp->gpwrap ||
+ if (READ_ONCE(rdp->gpwrap) ||
ULONG_CMP_GE(READ_ONCE(rcu_state.gp_seq),
READ_ONCE(rdp->gp_seq_needed)))
continue;